This invention relates to a method of isolating the fractions of Cordyceps sinensis and extracting the constituent H1-A, which can suppress the activated human mesangial cells, alleviate IgA nephropathy (Berger's disease), and prevent the disease from progressing to the uremia stage.
Recent studies have demonstrated the multiple pharmacological actions of Cordyceps sinensis (Clavicipitaceae), which is a fungus that develops stroma and is found on the larvae of the lepidoptera caterpillar. The pharmacological actions include:
1. Immune System PA0 2. Renal Function PA0 3. Cardiovascular System
In animals, the extracts of Cordyceps sinensis raise the phagocytic index of macrophage and stimulates the secretion of interleukin 1; it induces proliferation of splenic Thy-1 cells and stimulates the synthesis and secretion of IgM. It also stimulates the replication of T lymphocytes and increases the number of interleukin 2 receptors expressed on B lymphocytes. The aqueous extract increases the activity of natural killer cells in both normal subjects and leukemia patients.
Cordyceps sinensis reduces damages to renal tubules and protects the Na.sup.+, K.sup.+ -ATPase on cellular membranes, an action which is associated with a reduction in cellular lipid perioxidation. It can decrease chronic renal insufficiency. In rats, it can alleviate hematuria and reduce the elevation of serum creatinine.
An extract of Cordyceps sinensis increases the volume of blood flow in the coronary arteries of experimental animals. It also reduces resistance and pressure in arteries, brain, and peripheral vascular system. Adenosine, the main water-soluble constituent, acts to relax vascular smooth muscle and causes vasodilatation. Cordyceps sinensis also promotes platelet formation, helps prevent hypoxia, and acts as a monoamine oxiduse (MAO) inhibitor.
No purified compounds from Cordyceps sinensis have been used before to evaluate the above-mentioned pharmacological actions. None of the researches conducted on alleviating the histological symptoms of renal pathology were based on any animal model of IgA nephropathy.
Clinically, IgA nephropathy presents as paroxysmal hematuria and/or proteinuria, and it always runs a chronic course. The disease gradually progresses to uremia in 20% of adult patients in Taiwan. To date, no therapeutic agent has been shown to stop its progression. Hence there is a pressing need for development of a curative substance. The pathogenesis of IgA nephropathy is as follows:
Mesangial deposition of nephritogenic IgA immune complexes in glomeruli activates the resting mesangial cells. The activated mesangial cells start to release cytokines including interleukin 1 (IL-1), interleukin 6 (IL-6), and tumor necrosis factor .alpha. (TNF .alpha.). These cytokines cause mesangial cells to release growth factors such as platelet-derived growth factor (PDGF) and transforming growth factor-.beta. (TGF-.beta.) in addition to IL-1 and IL-6. The actions of these cytokines and growth factors are similar to that of autocrine system in which it induces a vicious cycle of mesangial proliferation with release of chemical mediators such as platelet activating factor (PAF), prostaglandin E.sub.2 (PGE.sub.2), thromboxane B.sub.2 (TXB.sub.2), neutral proteinase, and free radicals including superoxide union which all lead to the glomerular injury and sclerosis.
Clinically, IgA nephropathy generally presents as paroxysmal hematuria (microscopic or macroscopic) and/or proteinuria. This chronic disease typically runs an asymptotic course interspersed with periodic acute exacerbation. According to previous studies, it progresses to renal failure in 20 to 30% of cases in Spain and France; hence it can be inferred that each year 1 to 2% of the patients diagnosed with IgA nephropathy will progress to renal failure. Unfortunately, no treatment has been shown to arrest the progress of the condition. The etiology of IgA nephropathy is still unknown. However, the extensive deposition of both IgA and complement 3 (C3) on the mesangial area found in renal biopsy shows that the renal damage is probably caused by mesangial deposition of IgA immune complexes in association with activated alternative complement pathway. In brief, nephritogenic IgA immune complexes activate the resting mesangial cells to release cytokines such as interleukins 1 and 6 as well as tumor necrosis factor .alpha. (TNF .alpha.), causing mesangial cell proliferation accompanied by the release of growth factors including platelet-derived growth factor (PDGF) and transforming growth factor-.beta. (TGF-.beta.). Like autocrine, these cytokines and growth factors not only provoke a vicious cycle of mesangial cell proliferation, but also cause the mesangial cells to release free radicals such as superoxide anion (O.sub.2.sup.-) and H.sub.2 O.sub.2, and chemical mediators such as platelet activating factor (PAF), prostaglandins, thromboxane B.sub.2, and neutral proteinase, thereby inducing matrix accumulation, glomerular injury, and sclerosis.
It can be inferred from the above that the treatment of choice would ideally be based on preventing the formation of IgA immune complexes. However technological limitations in the field of immunology preclude these options. Hence attempt was made to settle for a second approach: using specialized isolation techniques, and the inventor started to work out a way to obtain natural products to extract bioactive agents that can suppress activated mesangial cells, thereby preventing their proliferation and the release of cytokines and growth factors. Once the activated mesangial cells have been effectively suppressed and their proliferation arrested, the process that leads to production of cytokines and growth factors can be brought to a halt. Hence the inventor selected in vitro suppression of activated mesangial cells as the screening method in the search for therapeutic agents.